Glass forming roll



Nov. 3,' 1942. J. H. SHERTS GLASS FORMING ROLL Filed Feb. 8, 1940 IN ENTOE ESHJHERTS HTTOE/VEK Patented Nov. 3, 1942 Gmss FORMING non. James Hervey Shorts, Pitt Pittsburgh Plate GI County, Pa., a corporation of Application February 8, 1940, Serial No. 317,828

1 Claim.

The present invention relates to the production of plate glass and more particularly to the forming rolls which constitute a part of the apparatus used in such production.

A primary object of the invention is the provision of a forming roll capable of withstanding, without warping, the severe heat conditions to which it is exposed during the manufacturing operations. 7

Other objects and advantages of my invention will become more apparent from the following detailed description of a preferred embodiment thereof.

One form of plate glass is obtained by rolling a body of molten glass into a sheet which is subsequently ground and polished. faces of the forming rolls are the molten glass, they are unevenly heated and warp, thus creating irregularities in the rolled sheet. By allowing for displacement of the rolls, the sheet must be of greater thickordinarily be the case if the forming rolls could be maintained in true align-, ment. Consequently more grinding is required to bring the two faces of the glass sheet to uniform parallelism and the manufacturing costs as well as material losses are increased.

I am aware that numerous improvements have been made to the earliest type of forming rolls;

including provisions for cooling them. These modifications in design of the roll structure have improved their performance, but there is still present a. decided tendency. for them to become substantially ne atives the other advantages gained through the newer developments.

Briefly stated, the present invention contemplates the use of a high silica content glass in the fabrication of forming rolls which are serviceable and almost entirely unaffected by the severe heat conditions incident to their use.

One embodiment of my invention is illustrated in the accompanying drawing, wherein:

Figure 1 is a fragmentary vertical sectional view of a glass tank and rolling apparatus employing forming rolls constructed in accordance with the provisions of the invention.

Figure 2 is a longitudinal section through one of the forming rolls; and

Figure 3 is a vertical sectional view, on a larger scale, through the roll taken at right angles to Figure 2.

Referring to the drawing, a glass tank I consburgh, l a., as'signor to ass Company, Allegheny Pennsylvania of the tank. The molten glass 2 flows between a pair of spaced forming or sizing'rolls 5, with the production of a. sheet'fi which is advanced over a plurality a suitable annealing'leer (not shown).

The structure of the rolls 5 constitutes the principal subject matter of this invention and it will be apparent that they could be substituted for the conventional forming rolls employed in Since the sur- -cient of thermal plugs 20. A cooling other types of plate glass rolling apparatus.

The rolls 5 comprise a plurality of rings III of high silica content glass suitably assembled and'locked together. A glassfrom which the rings iii are formed is designed to contain approximately 96 per cent of silicon dioxide admixed with a small percentage of boric oxide. A glass of this composition has a melting or softening point above 2500 F. and is capable of withstanding temperatures in the range of from 1800 to 2000 F. which are generally encountered in the production of plate glass. A more important characteristic of this glass is its coeflilinear expansion of about 8 10 per centlgrade degree, afactor which precludes distortion of the glass upon heating.

The rings ID are cast or molded with centrally projecting lugs ll (Fig. 3) which space the rings from an inner supporting cylinder l2 constituting the core of the forming roll. The cylinder H has formed in' its outer surface suitable splines or channels l3 into which the lugs ll fit; thus securing the rings ill to, and permitting their rotation with, the cylinder. Lateral displacement of the rings upon the cylinder is prevented by collars IQ, locked in position by nuts l5 threaded onto the cylinder. der I2 is journalled in bearings each end thereof and driven means (not shown) engaging a gear l8 secured Before assembling the faces of the rings iii are ground to insure a close fit assembled roll is machined or ground to a true cylindrical surface.

The ends of the cylinder ii are closed by dams or plugs 20 through which extend conduits Zl terminating centrally in distributing heads 22. Packing glands 23 secure the conduits H in the fluid, such as air or water is passed through the conduits 2i into the distributing heads 22 and is forced through openings 25 provided therein and aligned with openings 26 in the cylinder l2 into the space between the cylinder and the rings ill. The cooling fluid circulates toward the ends of the roll, as indicated by the arrows, flows into the cylinder l2 again The cylinll positioned at of rolls 1 and carried through Openings 29 discharged through conduit 30 swivelly connected to the cylinder. The forced cooling the rolls as described will maintain the temperature o! the supporting cylinder suiiiciently low to prevent distortion thereof.

A fused silica, such as is employed in the rings ID, has exhibited its ability to stand wide variations in' temperatures without iracturins and accordingly the rolls 5 are insured or a relative permanence. v

Since the forming rolls are cooled, the molten glass being rolled will not adhere thereto and thesheet production may be continued ior'long runs without interruption for repairs or cleaning. Again the low temperature 0! the rolls precludes surface erosion oi the discs by the fluxes of the molten glass and the original machined suriaces will not require intermittent refinishing.

through openings 28 and is leading to a Various other methods of supporting the glass rings it upon the inner cylinder l2 are possible. It should be pointed out, however, that the metal cylinder 12 will hav a greater coefllcient of linear expansion than the glass rings and proper allowance must be made therefor.

Accordingly it is desirable to retain forced cooling of the roll to prevent distortion oi the metal cylinder.

What I claim is:

A glass forming roll comprising a plurality of rings of high silica content glass having centrally projecting lugs positioned upon and spaced from an inner supporting cylinder, the ring lugs engaging suitable channels in the surface of the cylinder, and means for circulating a cooling fluid through the cylinder and the glass rings.

JAMES HERVEY SHEETS. 

